OpenDayLight's Virtual Tenant Networks
To support and better integrate with OpenStack's tenants, ODL has a specific module named Virtual Tenant Network (VTN).
VTN is one of the very interesting modules in ODL; we haven't discussed this yet. VTN integrates with OpenStack through the ML2 plugin. Technically, VTN is an SDN policy manager. It builds a list of tenants and their resources (virtual machines, networks, IP addresses, MAC addresses, policies, NAT, and so on).
Once we connect ODL and OpenStack using the ML2 plugin, any newly created tenant in OpenStack will be created in ODL's VTN too.
VTN allows users to design a virtual legacy L2/L3 network. Once the network design is finalized in VTN, it will get automatically mapped to the underlying physical network. This mapping is done via the ODL controller by injecting the required configuration to each individual switch or networking equipment, based on the southbound protocol supported by that networking gear.
The following picture from ODL...